Association between cognitive function and IL-18 levels in schizophrenia: Dependent on IL18-607 A/C polymorphism

Accumulating evidence suggests that immune system dysregulation is associated with debilitating neuro-development in schizophrenia (SZ). Cognitive impairment is a persistent feature that occurs during the onset of SZ and persists throughout the course of the disease. Early studies have found that elevated interleukin (IL)-18 interacts with IL18 polymorphism and is correlated with psychotic symptoms in SZ. This study aimed to investigate whether elevated IL-18 levels interacted with the-607 A/C polymorphism to determine cognitive decline in patients with chronic SZ. We recruited 693 inpatients and 422 healthy controls to measure IL-18 levels and genotype the -607 A/C polymorphism. Further, cognitive function was measured by the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). We found that IL-18 serum levels were higher in patients than those in healthy controls, and were not associated with IL18 -607 A/C in combined subjects or either patients or healthy controls, respectively. Moreover, -607 A/C was correlated with the visuospatial/ constructional index only in the patients. In addition, our research found that IL-18 levels were positively correlated to immediate memory only in patients with the C/C genotype, but not in patients with C/A or A/A genotype. This study suggests that the relationship of IL-18 with cognitive function depends on the IL18 -607 A/ C polymorphism of SZ patients.